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December 14, 2006

Geomagnetic storm incomingPosted by Patrick at 01:08 PM *

If your local forecast is for clear skies tonight, and your distance from the equator is the same or greater than ours, get outside and look up. You may get to see an aurora. Trust me, it’s worth going to some trouble to see.

For auroras, darker skies make a difference the further south you go, because the aurora will be more on the horizon than overhead. But direct lights or immediate lo-glo can keep you from your eyes dark-adapting they way you'd want anywhere.

At a given latitude, some locations will be better than others- a function of the magnetic field. Southern Ontario, for example, will get auroras far more often than Northern California, even though they're at the same latitude.

Keep an eye on NOAA- it updates regularly.

If NOAA shows auroras at your location and you can't see them, your camera still might capture them. Try a 15-30 second exposure. You'll want a tripod (beanbags or beanbaggy-wrist supports also work) and a remote control or shutter delay.

If you look at This gallery of a 2001 storm you can see that in northern states / Canada visibility is great even in towns. The Silicon Valley photo wouldn't have been possible in the valley itself- one needed to go into the foothills, with a line of hills hiding the valley's lights.

Right now, the Earth's magnetic field is tilted north, which works against seeing the Aurora.

The further north magnetic you are, the better your chance. Chicago, at 42N, has a much better chance than London, at 52N, because what counts is your magnetic, not Geographic latitude. Magnetically, London is 47N Mag, Chicago, 52N Mag. The Upper Peninsula of Michigan gets spectacular aurora, with an ideal combination of far north magnetic latitude and low light pollution. Indeed, on the UP, I was doing Aurora Shadow Puppets.

Bright aurora can often be seen even in cities -- the most brilliant one I ever saw was on a flight from PDX-ORD-STL on Nov 5, 2004. You could see the Aurora on landing at ORD, and at the parking lot of the St. Louis Airport.

The camera trick works even without a tripod -- hold a digital camera pointed north, expose for three-four seconds. If the image is green, then you're looking at Aurora. You may not be able to see the color, but the camera will.

This page has a simple "dial" of the solar wind and Earth's magentic field tilt (of the Bz component, the one we really care about.) As of this writing, Bz was about +9nT, which isn't promising, but it's also daylight. If, this evening, that number is well negative, that's a promising sign.

Keep an eye on NOAA and spaceweather- if it's looking good for Colorado, then anytime after twilight ends might have some visible. Given that the storm has already started, ealier is likely better than later, though.

Because I live in California I haven't had too much experience with them (twice seen from the ground in California, several times seen from airplanes further north), but I do know they can come and go. The best one I saw from the ground lasted 1 1/2 hours, where in just minutes it could change from an ordinary sky to spikes of light to subtle ripples and back to invisibility.

In 2001 there was an aurora visible from Tucson, AZ. I didn't see it -- with the mountains to the north and the orange glow of Phoenix confusing things if you avoided the mountains, but I know people who did. That probably isn't going to happen again even at the next solar max, however, because aurorae in the Western Hemisphere in general may become less frequent. The magnetic North Pole is moving very rapidly in the general direction of the geographic North Pole, and in a couple decades it will be on the other side, in Siberia rather than Canada, if the current motion continues.

According to the NOAA map (last updated just a few minutes ago), here in Massachusetts I ought to be at the southern edge of the good visibility area, but I can't see anything (except stars, so it can't be all that cloudy). Might be too much light pollution.

Bz still negative, Kp still 9. First reports from 43N (lower Michigan) and 40N (Ohio), so we're looking at current visibility to 50N Magnetic, at least in the eastern time zone.

Alas, I'm at 49N Magnetic, and it's cloudy.

Assuming this level holds for the next three-four hours, it should head southwards a bit as the sun gets further away.

On this map, if you're north of the KP7 curve and have clear skies, you've got a very good chance of seeing the Aurora, and if you're north of the KP5 line and it is clear, you're not reading this, you're outside gawking.

West coasters will have to wait a couple of hours, but Seattle looks solid, and Portland doesn't look too unlikely.

Bah. We've got a good, old-fashioned wind and rainstorm here (if it were on, say, the East Coast, about Florida, say, it might could be called mebbe a baby hurricane). Trees down. Powerlines down. Blizzard conditions in the Cascades.

Aurora? Heck, just try the wind and rain. Will need to power down soon as we're approaching the bad wind time.

I doubt I'll be able to see anything (Perth, Western Australia - far too far north). I will, however, keep an ear peeled for reports of giant carnivorous orchids, or mass blindness.

If there's anyone reading this in Tasmania, switch off the PC, switch off the lights, and go outside and look south. The Taswegians may actually be able to see something (and they're all isolated on a nice island if it does come to mass blindness and giant carnivorous orchids).

Didn't even try last night due to our building's outdoor lights, the cold, and predicted clouds, but 1) my 2006 Weather Calendar has a fabulous aurora photo for December and 2) I managed to dream I saw it (from some utterly unlikely place).

The power outage in large parts of the greater Portland area last night probably would have helped visibility, if it hadn't been for the accompanying clouds and wind and rain. (Gusts up to 60mph in urban areas, 99mph measured on Mt Hood).

For all of us who got yesterday's heads-up too late, there's still some hope for tonight and tomorrow. I just got a fresh alert from the IPS email list at 10:30 Eastern this morning, so while activity's apparently declining it won't be back to normal any time soon. Better yet, spacewaether.com is reporting "An X1-flare from sunspot 930 on Dec. 14th probably hurled a new cloud in our direction. (Confirmation from SOHO is pending.) If so, it would arrive on Dec. 16th and re-energize geomagnetic activity. Stay tuned!"

I was out late last night, bicycling through illuminated and secluded areas, but did not see any aurora, unfortunately.

The best aurora I'd ever seen had been in June of 1974 (if I'm recalling the date correctly). Because it was warm, it was possible to stay out for hours and watch. There was no color, but it covered a wide swatch of the sky. This was in upstate NY.

Luckily for us, the most spectacular astronomical events coming up are known to the second (time and space). Here's the location of the next 19 years of Total Solar Eclipses. (Or the next thousand years worth for the singularitan optimists.)

Total eclipses (partials are nothing- they share only the name*) are one event where once you see it, you understand exactly why people told you "No matter how good we tell you it is, it'll be better than that. You'll understand."

I've seen two. They're the most stunning, numinous, beautiful and unearthly experience I've had. And they give you an excuse to travel where you might not have expected to go,** and meet with an interesting crowd of fellow addicts.

* The difference between partials and totals? Eclipse chasers usually end up using analogies like "the difference between a kiss and a lover" because those are the only analogies that work.

** The deeply dedicated chasers I know have camped in Libyan deserts (2006), and are already planning their Mongolian (2008) or Easter Island (2010) trips. The dedicated with money have even seen ones like 2003 (Antarctica).

Davey and I have promised each other that someday we'll go to Fairbanks AK in March. Why? Because that's past the worst of the winter, and Fairbanks is \peak/ aurora territory -- if you go north from there you're likely to get a view from behind, which I'm told can be interesting but not as spectacular. There's a reason the U of AK at Fairbanks is the only(*) school with its own rocket range -- they take all sorts of interesting soundings.

(*) claim not checked against other schools. Void where prohibited. Contents sold -- no, wait, that was another thread.

CHip @ 36: On the night that ErikO was doing shadow puppets using the Aurora, we decided that the view was better if we looked south, rather than north. The entire northern sky was green, and it wasn't moving very much. Most of the action was straight up (lying down on the ground was a good way of seeing that), and as the night progressed, we eventually shifted around so that we were looking toward the southern horizon.

The one time I saw the aurora borealis, Marci and I were driving back from the Worldcon in Winnipeg, crossing North Dakota/Montana IIRC. I saw this glow in the northwestern sky, looking like glow from a city -- asked M if it could be an aurora, and from her knowledge of them from living in Alaska, said it wasn't.

Then it began doing the spikes and sheets thing. We pulled off the road and watched it for a good hour or so.

Not as amazing as the total solar eclipse I got to on the Wash/Oregon border (not all the best comments on the difference are sexual, Kathryn -- I liken it to Mark Twain's "the difference between the lightning and the lightning bug"). A cool thing to me, not generally commented on: we were in a river valley, and there was a visible fog-bank (very thin) right where the terminator went along. This makes perfect sense, mind you -- I just had never heard of anyone commenting on it. Maybe they were all too busy watching the sky?

Tom: I remember that total eclipse -- my parents offered to send me to friends of theirs who lived in Oregon. Nervous about leaving home (I was only ten), I said no. I've often wished I'd chosen otherwise.

I note that it is theoretically possible to see both the 2008 total solar eclipse and the start of the 2008 Worldcon. The last of the jetlag, the souvenirs of Novosibirsk*, the memories of unearthly light: all will add to your Worldcon experience, providing frisson otherwise requiring experienced lawful-neutral chemists.

* Better weather than Nunavut, Greenland, or Novaya Zemlya (home of Tsar Bomba!). Or go to Hami in China- 20 seconds less eclipse, but the driest weather- first seeing the easternmost tip of Kazakzstan and the Gobi and Taklamakan Deserts, as they're all in the neighborhood.

Kathryn from Sunnyvale: Thanks for the link to the picture gallery. I see a couple of pictures posted by people from Rochester, so at least it was seen here. A photo by someone in Ithaca (more or less in the same area, for the purpose of global phenomena) states that to the eye the aurora had been very dim, but was brought out in the photo by a long exposure time.